From 2352b6df1a69cf6264b3132c60c77b332d8231d3 Mon Sep 17 00:00:00 2001
From: Eddie Ruiz <32622519+Ed2uiz@users.noreply.github.com>
Date: Tue, 23 Jan 2024 11:37:10 -0500
Subject: [PATCH] feat: add as_ijx() convenience function

---
 R/utils.R | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/R/utils.R b/R/utils.R
index b520df1..93498f9 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -162,3 +162,22 @@ as_matrix <- function(x){
     return(as.matrix(mat))
   }
 }
+
+#' @title as_ijx
+#' @param x dgCMatrix
+#' @noRd
+as_ijx <- function(x){
+  # check that x is a dgCMatrix
+  if(!inherits(x = x, what = "dgCMatrix")){
+    stop("Invalid input. Only dgCMatrix is currently supported.")
+  }
+
+  # Convert dgc into TsparseMatrix class from {Matrix}
+  ijx <- as(x, "TsparseMatrix")
+
+  # Get dbMatrix in triplet vector format (TSparseMatrix)
+  # Convert to 1-based indexing
+  df = data.frame(i = ijx@i + 1, j = ijx@j + 1, x = ijx@x)
+
+  return(df)
+}